body {
    margin-bottom: 100px;
}

.nav {
    height: 50px;
    background: #192847;
}

.left-ul {
    display: flex;
    align-items: center;
    height: 50px;
}

.left-ul li {
    padding: 0 20px;
    color: aliceblue;
    opacity: 0.5;
    cursor: pointer;
}

.left-ul li:hover {
    opacity: 1;
}

.sell {
    position: relative;
}

.sell:hover .sell-wrapper {
    display: block;
}

.sell-wrapper {
    position: absolute;
    top: 50px;
    left: 0;
    display: none;
    width: 200px;
    padding: 20px;
    box-shadow: 0 0 10px rgba(255, 0, 0, 0.3);
    background: #fff;
}

.sell-wrapper:before {
    content: '';
    position: absolute;
    left: 0;
    top: -30px;
    width: 100%;
    height: 30px;
}

.sell-wrapper li {
    color: #000;
}

.radio-wrapper input[type='radio'] {
    display: none;
}

.radio-diy {
    display: inline-block;
    width: 10px;
    height: 10px;
    border: 1px solid #ddd;
}

.radio-wrapper input[type='radio']:checked + .radio-diy {
    background: goldenrod;
}

.checkbox-wrapper input[type='checkbox'] {
    display: none;
}

.checkbox-diy {
    display: inline-block;
    width: 10px;
    height: 10px;
    border: 1px solid #ddd;
    border-radius: 100%;
}

.checkbox-wrapper input[type='checkbox']:checked + .checkbox-diy {
    background: gold;
}

/* 多列等高 */

.dg-wrapper {
    display: flex;
}

.children-box {
    flex: 1;
    margin: 10px;
    padding: 4px;
    border: 1px solid #ddd;
    border-radius: 4px;
}

@media (max-width: 500px) {
    .dg-wrapper {
        flex-direction: column;
    }
}

/* 需要根据个数显示不同样式 */

.many-li-ul-flex-wrapper {
    display: flex;
}

.many-li-ul-flex-wrapper > .many-li {
    flex: 1;
}

.many-li-ul-nth-wrapper > li {
    width: 100%;
}

/* 向前选择：只显示第二个，把第一个隐藏掉 */
.many-li-ul-nth-wrapper > .many-li:nth-of-type(1):nth-last-child(3) {
    display: none;
}

/* 巧用CSS3伪类 */
.search-form .icon-search {
    color: #333;
}

.search-form .search-input:focus + .icon-search {
    color: aquamarine;
}

.search-form .number-input:invalid + .number-tip {
    color: #f00;
}

.search-form .number-tip {
    color: #333;
}

/* hover显示提示信息 */
.hover-span {
    position: relative;
}

.hover-span:hover:before {
    content: attr(data-title);
    position: absolute;
    top: -150%;
    white-space: nowrap;
}